Sur une nouvelle méthode de synthèse de δ-lactones cyclopenténiques

Abstract

Synthesis of two cyclopentenic δ-lactones, 1,3,4,4a,5,6-hexahydrocyclopenta[c]pyran-1-one and its analogue possessing a cyclopentenyl group bonded to the carbon atom 4a is described, starting from the cyclopentanone or cyclopentylidene cyclopentanone. The remarkable reactivity of the tosylhydrazones allows transformation of these compounds into substituted cyclopentenes, which lead to δ-lactones by cyclization. The conditions of cyclization depend on the nature of the cyclopentanone. The structure of the two δ-lactones is established by 1H and 13C nmr data, mass spectrometry, and, in one case, by X-ray analysis.